THE LUNDA STOVE came about in an attempt to improve the wood stove in general and to create a stove that could be built on-site and that also would improve both combustion and heating efficiency. It took a year to plan and build this stove. The result was very good. It is perhaps one of the world's best wood stoves with very high efficiency and the smoke is invisible and odorless when fired properly, except for a short time when ignited, which indicates very low emissions.
The Lunda Stove has a concrete frame. But so that it would not be too heavy, many tests were done with lightweight concrete mixtures that were subjected to fire tests. Once the concrete mixture was determined, molds were built to cast the outer casing in a single piece. This was done so that the stove would be completely smoke-tight. The interior is a rather complicated network of walls and ceilings that allows supply air to be taken in from the outside through a hole in the floor and which can then be taken directly into the combustion chamber floor or redirected so that it instead enters from the combustion chamber roof. The stove was designed to allow for reverse combustion when the supply air to the combustion chamber is taken from above and the flue gases pass out through the bottom of the combustion chamber and then pass on its outside and up to the convectors.
The combustion chamber is very well insulated to provide a high efficiency by allowing high combustion temperature. The principle of the stove is to first burn all gases as well as possible, and only when they have burned, take out the heat in the remaining flue gases. Most stoves are built so that the heat radiation from the hearth itself will contribute to the heating in the room. With this principle, you get worse combustion because there are heat losses in the combustion chamber and lower combustion temperatures.
The convectors consist of five tubes in each convector and which according to the manufacturer must be able to emit 5 kW. It is not likely that such an output will be achieved, but they have worked very well. They lower the temperature of the flue gases significantly, and with efficient firing, outgoing flue gas temperatures directly after the convectors are 90-160 degrees, which testifies to strong cooling of the flue gases in the combustion chamber can amount to 1000 degrees. The convectors have 4 fans of 200 mm diameter behind them and this makes a good contribution to both heat output and heat dissipation to the room. The fans are of the type found for cooling computers because they are the quietest and most energy-efficient fans that are possible to get hold of.
The stove acts as a heat store and the concrete is still warm up to 24 hours after firing. It gives a good heat distribution to the room. Otherwise, the basic idea with this stove is to spread the heat in the room where a large mass and a lot of wood should act as the actual heat layer. The room of 50 m2 keeps the temperature well throughout the night, even during the coldest winter nights.
The door on the stove was improved during the first winter. It turned out that it went sooted with each firing and that meant both poor visibility and a lot of cleaning work. The door was improved and has now become self-cleaning. This means that if soot occurs during firing, e.g. when firewood lies against the glass, the soot burns up in the latter part of the combustion phase. The door glass never needs to be cleaned of soot. It occurs after a while accumulating fly ash on the inside of the glass, but it is very easy to wipe off with a damp cloth.
The air intake is made from the bottom of the stove where a pipe is pulled through the floor of the room and opens out under the house. Taking the air from outside and having a damper for the intake means that you get complete control of the supply air. It also does not affect the house's ventilation system. Stoves that take the air out of the room always have problems with losses of heated air that pass out through the stove. The biggest problem, however, is that it is difficult to control the movement. If the house is tight, you need to either open windows or install a special valve to allow free airflow to the stove. If you have a sensor-controlled ventilation system, it can be negatively affected by the increased draft caused by the stove. The first test year with Kamin Lunda has proven the importance of taking the supply air from outside. It is always just as easy to light and fire in the stove once you have learned how to set the three dampers that the stove is equipped with.
The stove has also been built for functional aesthetics. By placing it in a corner, it is both central and still out of the way. Its shape is pentagonal to fit into the corner and the concrete surface is lasered with silicate paint that makes it both dense and beautiful.
The chimney is an insulated double mantled tube. The efficiency of the construction means that there is no need for chimney sweeping to remove the soot. It is a self-cleaning construction. No soot in the chimney! Only some ashes collected in the upper part of the stove have to be removed, and that is easily done once a year.) Of course, ashes are removed from the ash container and the burning chamber regularly.
The wood consumption at Station Lunda is 2-3 m3 per year. Wood heat is the only heat source.
Stove Lunda is one of the world's most efficient wood stoves. Far from the mediocre steel stoves sold in department stores and only a handful of stoves in the world can possibly be placed alongside The Lunda Stove.
Station Lunda has shown that wood stoves also can be improved.